This patch addresses two main issues: (1) There exist some non-fatal
errors in some of the hash algorithms. For exmaple, in float_hash and
complex_hash a certain part of the value is not included in the hash
calculation. See Tim's, Guido's, and my discussion of this on
python-dev in May under the title "fix float_hash and complex_hash for
64-bit *nix"
(2) The hash algorithms that use pointers (e.g. func_hash, code_hash)
are universally not correct on Win64 (they assume that sizeof(long) ==
sizeof(void*))
As well, this patch significantly cleans up the hash code. It adds the
two function _Py_HashDouble and _PyHash_VoidPtr that the various
hashing routine are changed to use.
These help maintain the hash function invariant: (a==b) =>
(hash(a)==hash(b))) I have added Lib/test/test_hash.py and
Lib/test/output/test_hash to test this for some cases.
diff --git a/Objects/classobject.c b/Objects/classobject.c
index cd0bb1d..f1dabfe 100644
--- a/Objects/classobject.c
+++ b/Objects/classobject.c
@@ -864,10 +864,7 @@
func = instance_getattr(inst, cmpstr);
if (func == NULL) {
PyErr_Clear();
- outcome = (long)inst;
- if (outcome == -1)
- outcome = -2;
- return outcome;
+ return _Py_HashPointer(inst);
}
PyErr_SetString(PyExc_TypeError, "unhashable instance");
return -1;
diff --git a/Objects/complexobject.c b/Objects/complexobject.c
index 42709ee..1a15a27 100644
--- a/Objects/complexobject.c
+++ b/Objects/complexobject.c
@@ -285,8 +285,7 @@
PyComplexObject *v;
{
double intpart, fractpart;
- int expo;
- long hipart, x;
+ long x;
/* This is designed so that Python numbers with the same
value hash to the same value, otherwise comparisons
of mapping keys will turn out weird */
@@ -302,7 +301,7 @@
#endif
if (fractpart == 0.0 && v->cval.imag == 0.0) {
- if (intpart > 0x7fffffffL || -intpart > 0x7fffffffL) {
+ if (intpart > LONG_MAX || -intpart > LONG_MAX) {
/* Convert to long int and use its hash... */
PyObject *w = PyLong_FromDouble(v->cval.real);
if (w == NULL)
@@ -314,36 +313,18 @@
x = (long)intpart;
}
else {
- fractpart = frexp(fractpart, &expo);
- fractpart = fractpart * 2147483648.0; /* 2**31 */
- hipart = (long)fractpart; /* Take the top 32 bits */
- fractpart = (fractpart - (double)hipart) * 2147483648.0;
- /* Get the next 32 bits */
- x = hipart + (long)fractpart + (long)intpart + (expo << 15);
- /* Combine everything */
+ x = _Py_HashDouble(v->cval.real);
+ if (x == -1)
+ return -1;
if (v->cval.imag != 0.0) { /* Hash the imaginary part */
/* XXX Note that this hashes complex(x, y)
to the same value as complex(y, x).
Still better than it used to be :-) */
-#ifdef MPW
- {
- extended e;
- fractpart = modf(v->cval.imag, &e);
- intpart = e;
- }
-#else
- fractpart = modf(v->cval.imag, &intpart);
-#endif
- fractpart = frexp(fractpart, &expo);
- fractpart = fractpart * 2147483648.0; /* 2**31 */
- hipart = (long)fractpart; /* Take the top 32 bits */
- fractpart =
- (fractpart - (double)hipart) * 2147483648.0;
- /* Get the next 32 bits */
- x ^= hipart + (long)fractpart +
- (long)intpart + (expo << 15);
- /* Combine everything */
+ long y = _Py_HashDouble(v->cval.imag);
+ if (y == -1)
+ return -1;
+ x += y;
}
}
if (x == -1)
diff --git a/Objects/floatobject.c b/Objects/floatobject.c
index 69b66b7..29ade28 100644
--- a/Objects/floatobject.c
+++ b/Objects/floatobject.c
@@ -59,7 +59,13 @@
#endif
#ifndef LONG_MAX
+#if SIZEOF_LONG == 4
#define LONG_MAX 0X7FFFFFFFL
+#elif SIZEOF_LONG == 8
+#define LONG_MAX 0X7FFFFFFFFFFFFFFFL
+#else
+#error "could not set LONG_MAX"
+#endif
#endif
#ifndef LONG_MIN
@@ -357,12 +363,12 @@
return (i < j) ? -1 : (i > j) ? 1 : 0;
}
+
static long
float_hash(v)
PyFloatObject *v;
{
double intpart, fractpart;
- int expo;
long x;
/* This is designed so that Python numbers with the same
value hash to the same value, otherwise comparisons
@@ -379,7 +385,7 @@
#endif
if (fractpart == 0.0) {
- if (intpart > 0x7fffffffL || -intpart > 0x7fffffffL) {
+ if (intpart > LONG_MAX || -intpart > LONG_MAX) {
/* Convert to long int and use its hash... */
PyObject *w = PyLong_FromDouble(v->ob_fval);
if (w == NULL)
@@ -393,14 +399,9 @@
else {
/* Note -- if you change this code, also change the copy
in complexobject.c */
- long hipart;
- fractpart = frexp(fractpart, &expo);
- fractpart = fractpart * 2147483648.0; /* 2**31 */
- hipart = (long)fractpart; /* Take the top 32 bits */
- fractpart = (fractpart - (double)hipart) * 2147483648.0;
- /* Get the next 32 bits */
- x = hipart + (long)fractpart + (long)intpart + (expo << 15);
- /* Combine everything */
+ x = _Py_HashDouble(v->ob_fval);
+ if (x == -1)
+ return -1;
}
if (x == -1)
x = -2;
diff --git a/Objects/funcobject.c b/Objects/funcobject.c
index b976eab..d9ce027 100644
--- a/Objects/funcobject.c
+++ b/Objects/funcobject.c
@@ -231,10 +231,12 @@
func_hash(f)
PyFunctionObject *f;
{
- long h;
+ long h,x;
h = PyObject_Hash(f->func_code);
if (h == -1) return h;
- h = h ^ (long)f->func_globals;
+ x = _Py_HashPointer(f->func_globals);
+ if (x == -1) return x;
+ h ^= x;
if (h == -1) h = -2;
return h;
}
diff --git a/Objects/methodobject.c b/Objects/methodobject.c
index 8b67a87..580bb2f 100644
--- a/Objects/methodobject.c
+++ b/Objects/methodobject.c
@@ -172,7 +172,7 @@
meth_hash(a)
PyCFunctionObject *a;
{
- long x;
+ long x,y;
if (a->m_self == NULL)
x = 0;
else {
@@ -180,7 +180,13 @@
if (x == -1)
return -1;
}
- return x ^ (long) a->m_ml->ml_meth;
+ y = _Py_HashPointer(a->m_ml->ml_meth);
+ if (y == -1)
+ return -1;
+ x ^= y;
+ if (x == -1)
+ x = -2;
+ return x;
}
PyTypeObject PyCFunction_Type = {
diff --git a/Objects/object.c b/Objects/object.c
index 9a0e87c..9ed03b2 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -33,6 +33,8 @@
#include "Python.h"
+#include "mymath.h"
+
/* just for trashcan: */
#include "compile.h"
#include "frameobject.h"
@@ -507,6 +509,62 @@
return result;
}
+
+/* Set of hash utility functions to help maintaining the invariant that
+ iff a==b then hash(a)==hash(b)
+
+ All the utility functions (_Py_Hash*()) return "-1" to signify an error.
+*/
+
+long
+_Py_HashDouble(v)
+ double v;
+{
+ /* Use frexp to get at the bits in the double.
+ * Since the VAX D double format has 56 mantissa bits, which is the
+ * most of any double format in use, each of these parts may have as
+ * many as (but no more than) 56 significant bits.
+ * So, assuming sizeof(long) >= 4, each part can be broken into two longs;
+ * frexp and multiplication are used to do that.
+ * Also, since the Cray double format has 15 exponent bits, which is the
+ * most of any double format in use, shifting the exponent field left by
+ * 15 won't overflow a long (again assuming sizeof(long) >= 4).
+ */
+ int expo;
+ long hipart;
+
+ v = frexp(v, &expo);
+ v = v * 2147483648.0; /* 2**31 */
+ hipart = (long)v; /* Take the top 32 bits */
+ v = (v - (double)hipart) * 2147483648.0; /* Get the next 32 bits */
+
+ return hipart + (long)v + (expo << 15); /* Combine everything */
+}
+
+long
+_Py_HashPointer(p)
+ void *p;
+{
+#if SIZEOF_LONG >= SIZEOF_VOID_P
+ return (long)p;
+#else
+ /* convert to a Python long and hash that */
+ PyObject* longobj;
+ long x;
+
+ if ((longobj = PyLong_FromVoidPtr(p)) == NULL) {
+ x = -1;
+ goto finally;
+ }
+ x = PyObject_Hash(longobj);
+
+finally:
+ Py_XDECREF(longobj);
+ return x;
+#endif
+}
+
+
long
PyObject_Hash(v)
PyObject *v;
@@ -514,8 +572,9 @@
PyTypeObject *tp = v->ob_type;
if (tp->tp_hash != NULL)
return (*tp->tp_hash)(v);
- if (tp->tp_compare == NULL)
- return (long) v; /* Use address as hash value */
+ if (tp->tp_compare == NULL) {
+ return _Py_HashPointer(v); /* Use address as hash value */
+ }
/* If there's a cmp but no hash defined, the object can't be hashed */
PyErr_SetString(PyExc_TypeError, "unhashable type");
return -1;